Controlled etching and regrowth of tunnel oxide for antenna-coupled metal-oxide-metal diodes

Abstract

The authors have designed a new procedure for fabrication of infrared (IR) sensors. These sensors consist of a dipole antenna coupled with a metal-oxide-metal (MOM) (Al–AlOx–Pt) diode. The surface of electron beam evaporated Al, serving as one of the electrodes, is cleaned using an Ar plasma, followed by in situ controlled growth of the tunneling oxide, AlOx. The antenna, its leads, and the overlap of the Al and Pt electrodes that defines the MOM overlap area are all defined using electron beam lithography. The MOM overlap area of these devices is as small as 50×80 nm2. Features of our process include the use of dissimilar metals for the formation of the MOM diode, small MOM diode size, and controlled etching and regrowth of the tunneling oxide. A CO2 laser at 10.6 μm was used for the IR characterization of these sensors. Current-voltage and IR measurements are presented. The normalized detectivity (D∗) for these devices was found to be 2.13×106 cm Hz1/2 W−1.